Modulation coding scheme selection in a wireless communication system

Abstract

A base station and method for selecting a modulation coding scheme (MCS) in an OFDM communication system, includes a first step 500 of estimating the channel response on each antenna based on the uplink feedback. A next step 502 includes calculating transmit weights from the uplink feedback. A next step 504 includes computing a beamformed Carrier-to-Interference plus Noise Ratio based on a broadcast Carrier-to-Interference plus Noise Ratio and the transmit weights and the channel response. A next step 506 includes choosing a best modulation coding scheme for a beamform allocation using the beamformed CINR. A best antenna gain and frequency band can also be chosen using the beamformed CINR.

1 . A method for selecting a modulation coding scheme in a communication system, the method comprising the steps of:
 estimating a channel response on each antenna based on an uplink transmission;   calculating transmit weights, to be used for a beamformed transmission, from the uplink transmission;   computing a beamformed Carrier-to-Interference plus Noise Ratio based on a broadcast Carrier-to-Interference plus Noise Ratio and the transmit weights and the channel response,   choosing a best modulation coding scheme for a beamforming allocation using the beamformed Carrier-to-Interference plus Noise Ratio; and   communicating using the chosen modulation coding scheme.   
   
   
       2 . The method of  claim 1 , wherein the choosing step also includes choosing a best antenna gain using the beamformed Carrier-to-Interference plus Noise Ratio. 
   
   
       3 . The method of  claim 1 , wherein the choosing step also includes choosing a best Adaptive Modulation and Coding band using the beamformed Carrier-to-Interference plus Noise Ratio. 
   
   
       4 . The method of  claim 1 , wherein the uplink transmission is a from an uplink sounding channel. 
   
   
       5 . The method of  claim 1 , wherein the uplink transmission is from a Channel Quality indicator channel. 
   
   
       6 . The method of  claim 1 , wherein the computing step includes calculating
     ΔCINR =Avg over allocation (10 log(| Hν   TxAA | 2 ))−(10 log(| Hν   broadcast | 2 ))   
     and calculating the new beamformed CINR based on a reported physical CINR (PCINR) and the ΔCINR. 
   
   
       7 . The method of  claim 6 , wherein ν broadcast  includes the cyclic shift transmit diversity response used on the broadcast transmission. 
   
   
       8 . The method of  claim 1 , wherein the choosing step includes choosing the best MCS for a first beamformed allocation to a subscriber station. 
   
   
       9 . A method for selecting a modulation coding scheme in an OFDM communication system, the method comprising the steps of:
 estimating the channel response on each antenna based on an uplink transmission from a subscriber station;   calculating transmit weights, to be used for a beamformed transmission to the subscriber station, from the uplink transmission;   computing a beamformed Carrier-to-Interference plus Noise Ratio based on a broadcast Carrier-to-Interference plus Noise Ratio and the transmit weights and the channel response,   choosing a best modulation coding scheme for a first beamform allocation to the subscriber station using the beamformed Carrier-to-Interference plus Noise Ratio; and   communicating with the subscriber station using the chosen modulation coding scheme.   
   
   
       10 . The method of  claim 9 , wherein the choosing step also includes choosing a best Adaptive Modulation and Coding band using the beamformed Carrier-to-Interference plus Noise Ratio. 
   
   
       11 . The method of  claim 9 , wherein the uplink transmission is a from an uplink sounding channel. 
   
   
       12 . The method of  claim 9 , wherein the uplink transmission is from a Channel Quality indicator channel. 
   
   
       13 . The method of  claim 9 , wherein the computing step includes calculating
     ΔCINR =Avg over allocation (10 log(| Hν   TxAA | 2 ))−(10 log(| Hν   broadcast | 2 ))   wherein ν broadcast  includes the cyclic shift transmit diversity response used on the broadcast transmission, and calculating the new beamformed CINR based on the reported physical CINR (PCINR) and the ΔCINR.   
   
   
       14 . The method of  claim 9 , wherein the choosing step includes choosing the best MCS for subsequent beamform allocations to a subscriber station. 
   
   
       15 . A base station operable to select a modulation coding scheme for communication with a subscriber station in a communication system, the base station comprising a processor operable to estimate the channel response on each antenna based on an uplink transmission from the subscriber station, calculate transmit weights, to be used for a beamformed transmission to the subscriber station, from the uplink transmission, compute a beamformed channel response based on the transmit weights and the channel response, translate a broadcast Carrier-to-Interference plus Noise Ratio into a beamformed Carrier-to-Interference plus Noise Ratio, choose a best modulation coding scheme for a beamform allocation using the beamformed Carrier-to-Interference plus Noise Ratio, and communicate with the subscriber station using the chosen modulation coding scheme.